Humans have been cultivating crops since before recorded time. The earliest and most successful growing locations combined good growing conditions, such as plenty of water and sunlight with good fertile soil conditions. However, as the human population continues to expand, ever more crops are required. Out of necessity crop science advances have been made, including using fertilizer to make the soil more fertile and advancing plant and crop genetics to increase crop yields from the same acreage. As well many different types of irrigation systems have been developed to extend the amount of plantable area.
More recently global warming has become an issue. Global warming has the potential to alter, on a large scale, weather patterns, including the amount and location of rainfall. Predictions have been made of reduced rainfall in certain areas and desertification as a result in extreme cases. This could affect the ability to raise crops in large areas of what is now arable land.
Water consumption is also an issue. As the world population grows, more and more water is used for domestic as well as industrial purposes. While efforts are being made to treat the waste water that is produced, this is not always done appropriately. Water shortages are predicted by some in the future. Further, in certain soil conditions, surface watering can be counterproductive. For example, in southwestern Australia, subsurface salt has been brought to the surface by surface over watering, essentially sterilizing large areas to conventional crop growing, by increasing the surface salt levels to those at which crops will no longer grow.
One solution to a lack of water for agriculture in a region is to use large scale diversions of fresh water sources such as rivers, such as occur in the south western states of the USA. Another solution is to tap into underground aquifers and extract water from deep within the earth to use on the surface to grow crops. However, generally a location that has little or no water, such as a desert or semi desert, is also characterized by high evaporation rates, meaning that surface water evaporates quickly upon being exposed. Water that evaporates is no longer available for any plants or crops and is thus wasted from crop growing or an agricultural point of view. A significant amount of the water used in traditional surface sprinkler irrigation is lost through evaporation, before it can ever be used by the plants being watered.
As a result attempts have been made to use more direct and efficient watering methods which reduce the likelihood evaporation such as drip irrigation. In this technique, small feeder or water tubes are provided to each plant which drip water onto the base of the plant. However, while efficient in reducing the amount of water used, because it is applied in small amounts directly to the individual plants and root systems, there are still problems with water loss due to evaporation. For one, the rate of evaporation and the need for water varies depending upon the weather, the temperature, the relative humidity and the like. This, providing a steady drip rate will result in over watering in some cases and under watering in other cases. Providing a variable drip rate is very difficult.
In another attempt underground water lines have been used to feed water directly to the root systems of plants. However, these suffer from the invasion of fibrous roots seeking water which can block the tubes and disrupt the water distribution to the rest of the system. Underground delivery of the irrigation water may be preferred when the water contains bacteria, such as untreated grey water. In this case it is preferred to irrigate the plants without directly exposing surface plants and animals to any such potentially harmful bacteria.
What is desired is a form of water conserving watering system and method that is efficient in delivering irrigation water to plants, without exposing the water to excessive evaporation, which can deliver the correct amount to water as needed by the plant, and which is less vulnerable to the harmful and obstructive effects of roots and the like. Most preferably such a system would be simple and easy to use and located underground to mitigate the harmful effects of contaminated source water. Most preferably it would be largely passive and yet also automatically provide the correct amount of water that might be needed to optimize plant growth. Such a system would need to deliver the appropriate amount of water as and when needed according to the moisture conditions of the soil around the plants being so watered to be the most efficient.